Can a corpse have an orgasm?

It’s not entirely unlikely [1]. The clue comes from patients with spinal cord injuries. Let’s start with the spinal cord, and we’ll come back to dead bodies in a bit.

Traffic Jam

The spinal cord–a long thin bundle of nervous tissue running from the base of the skull to just above the pelvis–provides an essential connection between the brain and body. Before you make any conscious movement, signals from your brain travel down your spinal cord. If the spinal cord were a highway, the southbound exit signs might read “heart”, “wrist and elbow”, “hip”, “foot”, etc. Signals from the brain take the appropriate exit, and that is how all of your peripheral muscles receive instructions to move. There are northbound lanes on this highway as well, traversed by sensory signals traveling from your skin or muscles up to the brain. A spinal cord injury is like a multi-lane accident on this highway. Signals can no longer pass the spot; traffic is blocked, often in both directions. The extent of the debacle depends on where the accident is–if the highway is blocked only near the southernmost exit, traffic on most of the highway will continue as normal. However, if the accident is further north, more of the exits are no longer accessible from the hub of activity, the brain.

While the highway analogy explains how much of our motor and sensory systems function, there are some circuits that don’t need access to the brain to create movement. Are you familiar with the knee jerk reflex? Or has your hand ever instantly flown backwards when you’ve accidentally touched a hot pan? These extraordinarily quick movements (”reflexes”) involve sensory information coming in, traveling to the spinal cord, and then coming immediately back to the limb to activate the muscle. Reflex arcs reduce the amount of traffic on the spinal cord highway and allow some muscle functions to occur quickly without involving the brain.

Importantly, some reflexes are part of the autonomic nervous system, distinct from the somatic system governing conscious movement and sensory perception. The autonomic nervous system controls the function of our internal organs, regulating heart rate, breathing, etc. These circuits do not rely heavily on the spinal cord highway, although they do connect to it at certain points. An orgasm is controlled by the autonomic nervous system, which explains why it is felt internally and throughout the body rather than just at the site of stimulation [1]. But what and where is the exact reflex circuit? How is it different from arousal circuits? And how are they impacted by spinal cord injury?

Ladies First

Do you prefer psychogenic or reflexogenic arousal methods? Say what? Watching porn, sexting your Tinder date, imagining yourself with Karl (sorry not sorry, it’s Love Actually season!) or Jackson (yes I still watch Grey’s Anatomy) are all types of psychogenic arousal, arousal that starts with your brain. Reflexogenic arousal, on the other hand, occurs via manual stimulation. In a 1995 study, Dr. Sipski, a well-known sex and spinal cord expert then at the Kessler Institute for Rehabilitation in NJ, recruited women

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with spinal cord injuries and uninjured control subjects to her lab. Each subject experienced alternating 12-minute sessions of watching an erotic video and watching the video with added manual stimulation. Arousal was quantified in terms of vaginal pulse amplitude (VPA), which is essentially a measure of blood flow to the vagina. While both injured and uninjured control subjects reported feeling aroused during the segments with just audiovisual stimulation, women with complete spinal cord injuries at T6 (the 6th thoracic segment, around mid-rib cage level) or above did not show physiological arousal as measured by VPA while watching the video. When manual stimulation was added, however, these women responded just as strongly in terms of VPA as the control subjects [2]. How does this work?

Think back to the highway. Essentially, if the arousal stimulus starts in the brain (as it would for audiovisual stimulation) and tries to travel down the spinal cord to get the party started, the signal can’t move far enough south if there is an injury (highway traffic jam!) in between. However, if the stimulation is coming in not from the eyes or ears but at a more southern exit (e.g. manual stimulation of the vagina), the northern traffic jam is not an obstacle to physiological arousal (increased blood flow, lubrication). Manual stimulation can generate arousal via a local reflex arc that doesn’t require information passing through the upper spinal cord, just a quick connection to the local spinal cord segment.

It is important to realize that while women with spinal cord injuries may be able to produce the physical signs of arousal such as lubrication and increased blood flow to the clitoris, they sometimes cannot actually perceive lubrication or even penetration. While the circuits controlling tissue blood flow and lubricant production can be controlled by reflex arcs, perception always occurs in the brain. For you to be consciously aware of something happening to your body, that information must somehow reach the brain, and spinal cord injuries often prevent that delivery of information.

When Harry Met Sally

What about orgasm–the rhythmic contraction of pelvic muscles, muscle spasms throughout the body, the feeling of euphoria? In a later but similar study utilizing the same alternating sessions, Sipski’s research group found that only 17% of women with complete spinal cord injury at S2-5 (sacral segments 2-5, the very bottom of the spinal cord) were able to achieve orgasm while 59% of patients with lesions elsewhere in the spinal cord could reach climax [3]. In this case, orgasm was self-reported by the subjects, but claims were augmented with heart rate and respiration measurements. The percentage of orgasmic success drops so significantly with sacral spinal cord injury because the reflex arc important for orgasm connects to the spinal cord here. You might wonder how there is euphoric feeling associated with orgasm if an injury is blocking paths to the brain. There are some direct paths from the autonomic nervous system to the brain that bypass the spinal cord. It has been suggested that the vagus nerve (known for its role in many internal functions such as heart beat and digestion) might provide a direct link between vagina or cervix and the brain [4].

For every study on female sexual function after spinal cord injury, there seem to be hundreds on male sexual function (shocker!). We therefore know quite a bit about the neural underpinnings of erection, ejaculation, and climax [reviewed in 5].

As in females, male erection can be triggered by manual stimulation via a reflex arc. A nerve in the penis connects to the sacral segments of the spinal cord and triggers the extra blood flow underlying erection. No brain involvement necessary! (Checkmate, Brain Jerry). As in women, male psychogenic arousal (audiovisual, imagination, etc.) travels through a middle region of the spinal cord and can be disrupted in the case of injury to the upper portion of the spinal cord.

Ejaculation comprises both the emission and expulsion of semen. Emission relies on reflex connections in the thoracic and lumbar (middle) regions of the spinal cord to cause contractions in the internal reproductive organs while expulsion relies on the a reflex in the sacral (lower) segments and their connection with the pelvic floor muscles. Unfortunately, because multiple spinal regions are involved, a majority of men with spinal cord injury have difficulty with natural ejaculation, and retrograde ejaculation is not uncommon. Extremely premature ejaculation, triggered by mere sexual thought, is another common problem for men with lesions in the lower spinal cord. If parts of both reflexes are intact, however, using a high amplitude vibrator along with manual stimulation has been shown to greatly increase likelihood of ejaculation. Does this preclude orgasm? Not necessarily. As in women, many men with complete spinal cord injury report experiencing orgasm, even in the absence of ejaculation.

You make a grown man cry, you make a dead man come

So, back to dead bodies. In her brilliant and entertaining book Bonk: The Curious Coupling of Science and Sex, Mary Roach explains that some beating heart cadavers (bodies dead by all medical definitions but being kept on a ventilator for organ donation) can still demonstrate reflex reactions if a particular nerve is stimulated in just the right way. It’s quite possible that someone could induce an orgasm in a beating heart cadaver by stimulating the sacral reflex arc. But I don’t think that research study will be approved anytime soon.